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C and Assembly Mixed-Mode Hex comparison program

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C and Assembly Mixed-Mode Hex comparison program

21 Days Ago

Hi, I have an assignment where i have to write a C and assembly mixed-mode program.

The c program takes in two characters which stand for two hex characters.
The assembly procedure then passes each character in turn to a C function which determines if the character is a valid ASCII HEX digit (namely 0-F).
If both characters are valid the assembly language procedure then compares the two HEX digits and returns the larger to the main program.
The main C program then prints out the larger digit.

I am unsure how to do no. 2, namely, how to determine if it's a valid ASCII HEX digit or just garbage. Suggestions?

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21 Days Ago

Could we see what you have so far?

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20 Days Ago

So far I have my C file taking in 2 characters:

 Help with Code Tags 
 Assembly Syntax (Toggle Plain Text) 
    char char1, char2;
    printf ("Enter a character: ");
    scanf ("%c", &char1);
 
    while (getchar () != '\n')//so that the program doesn't take in the carriage return as input
        continue;
 
    printf ("Enter another character: ");
    scanf ("%c", &char2);
 
    while (getchar () != '\n')//so that the program doesn't take in the carriage return as input
        continue;
    char char1, char2;
    printf ("Enter a character: ");
    scanf ("%c", &char1);
    
    while (getchar () != '\n')//so that the program doesn't take in the carriage return as input
        continue;
    
    printf ("Enter another character: ");
    scanf ("%c", &char2);
    
    while (getchar () != '\n')//so that the program doesn't take in the carriage return as input
        continue;

And I'm just not sure how to verify if their HEX or just normal characters (so either 0-9 or A-F). I was thinking I could just do a bunch of if statements comparing each of them (or make a HEX array, and for loop through it comparing along the way), but is there a better way to do this?

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20 Days Ago

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Originally Posted by HypnotiqBIG

So far I have my C file taking in 2 characters:
Help with Code Tags

Assembly Syntax (Toggle Plain Text)
    char char1, char2;
    printf ("Enter a character: ");
    scanf ("%c", &char1);
 
    while (getchar () != '\n')//so that the program doesn't take in the carriage return as input
        continue;
 
    printf ("Enter another character: ");
    scanf ("%c", &char2);
 
    while (getchar () != '\n')//so that the program doesn't take in the carriage return as input
        continue;
char char1, char2; printf ("Enter a character: "); scanf ("%c", &char1); while (getchar () != '\n')//so that the program doesn't take in the carriage return as input continue; printf ("Enter another character: "); scanf ("%c", &char2); while (getchar () != '\n')//so that the program doesn't take in the carriage return as input continue;
And I'm just not sure how to verify if their HEX or just normal characters (so either 0-9 or A-F). I was thinking I could just do a bunch of if statements comparing each of them (or make a HEX array, and for loop through it comparing along the way), but is there a better way to do this?

C has a function called isxdigit which checks if the character is 0 -9 or a - f maybe you could use that...